I'm 36. And I hate to start listing off my various health issues, because they're fairly extensive and I always feel that people will think I'm just trying to be the center of attention. "HEY LOOK AT HOW MESSED UP I AM!" So I usually try to just gloss over the whole story and cut to the chase. Be nonspecific. If asked, I'll be honest, but for the sake of concision, I'll try to keep it brief.
Firstly, I've been slinging tires for a living for 16 years, and when you add the repetitive motion to some issues that required POWERFUL immunosuppression, my joints are worn well past their 36 years. My right shoulder actually has moderate arthritis that from time to time limits my range of movement and sometimes will hurts for days on end. I have also had many medical treatments that permanently altered my blood chemistry and nervous system, so I frequently suffer from muscle cramps, have tinnitus in my right ear, and peripheral neuropathy that affects my hands and feet. Thankfully, the neuropathy doesn't interfere with my ability to play, but for a reference point, here's a short example: I was walking across my kitchen and every time I took a step I heard a "click". I thought the laminate had come loose, but it happened wherever I stepped. Turns out there was a penny stuck to the bottom of my foot. I couldn't feel it. If I step on something sharp that thing is ALL THE WAY TO THE HILT before i notice, and yanking it back out is a lot more noticeable that it going in. My stamina is not great, and my wonky shoulder combined with a significant amount of muscle loss from systemic coriticosteroid therapy means I usually have to get a helper for heavy gear, for sure if there are stairs involved.
But what I figure is if you want to do something badly enough, you find a way to make it work. I usually get my youngest brother to roadie for me in exchange for seeing shows for free. Maybe it's scaling back your gigging, maybe it's getting some helping hands, or maybe you get some carts or dollies or whatever you need to move your gear around.